Based on an integrated luminosity of 1.61 fb−1e+e collision data collected with the KLOE detector at DAΦNE, the Frascati ϕ-factory, a search for the P- and CP-violating decay η → π+π has been performed. Radiative ϕ → ηγ decay is exploited to access the η mesons. No signal is observed in the π+π invariant mass spectrum, and the upper limit on the branching fraction at 90% confidence level is determined to be ℬ(η → π+π) < 4.9 × 10−6, which is approximately three times smaller than the previous KLOE result. From the combination of these two measurements we get ℬ(η → π+π) < 4.4 × 10−6 at 90% confidence level.

Язык оригиналаанглийский
Номер статьи47
Число страниц11
ЖурналJournal of High Energy Physics
Номер выпуска10
СостояниеОпубликовано - 1 окт 2020

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